1. Technical Field
The present invention relates generally to couplings. More particularly, it relates to self-sealing vent pipe couplings having a gasket and mechanical locking device for advantageous use on pipes, tubes or vents formed of sheet material.
2. Related Art
Previously, new laws have required the use of new fuel burning appliances that capture more heat from each unit of fuel consumed. For example, home heating appliances come under the higher efficiency requirements. As higher efficiency heaters have evolved, they have expelled cooler exhaust gases resulting in reduced or insufficient flue draft. Ultimately, boilers and furnaces were created (Category II, III and IV) that could no longer be vented by negative pressure systems that rely on natural draft, but rather required the exhaust gases to be pressurized for the purpose of removing them from the premises.
As a by-product of low flue gas temperatures, condensation could now occur within exhaust systems and mix with chemical compounds to form acidic environments. To rectify this problem, plastic vents and other systems were developed and consequently used. Unfortunately, plastic vents due to high failure rates, are now either suspect or illegal.
Other contemporary venting systems have been found to be cumbersome to install, require many field modifications and employ manufacturing methods and product designs that render the long term performance of these vents questionable. For example, modifications may consist of cleaning ends of components with solvents or alcohol before applying sealants from tubes or other means to the component for the purpose of rendering the joint leakproof. Contemporary systems may also require joints to be held steady for 24 hours or until the applied sealants have cured, thus necessitating a waiting period before the heating unit can be operated. In systems currently available, this waiting period is often ignored, since the installer would have to return to the job site on the following day to check the system for tightness and to start-up the heating unit. As a result, for logistical and monetary reasons, manufacturers instructions are often ignored and the system's integrity compromised from the start.
U.S. Pat. No. 4,874,191 issued to Green and assigned to Heat-Fab, Inc. discloses a flue gas connector for joining together the ends of flue gas conduits by means of locking tabs on the outer surface of one flue gas conduit which may be bent over a locking ring or the other flue gas conduit. One disadvantage of this system is that the gasket is not integral with the coupling. Another disadvantage is that the process requires additional steps, such as cleaning of the inside of the female end and outside of the male end before applying silicone from a tube, during the installation process to provide a gasket thereon. A further disadvantage is that as the conduit is placed in a flue (e.g., a brick flue), the tabs 20 may inadvertently be pulled backward when contacting the interior of the flue, thus disconnecting the coupling.
Accordingly, it is a feature of this invention to provide pipe, vent or tube coupling without the disadvantages of the related art. Furthermore to provide a coupling to provide a leak-proof (gases and liquids) conduit from the heating equipment to the outside of residential/industrial/commercial spaces that is easy to install, minimizes the effects of corrosive condensates within the vent tube, or pipe, and eliminates installer errors or omissions.